After creating a drawing area, the application may want to
connect to:

Mouse and button press signals to respond to input from the
user. Use the gtk.Widget.add_events()
method to enable events you wish to receive. To receive keyboard events, you
will need to set the gtk.CAN_FOCUS flag on the drawing
area

The "realize" signal to take any necessary actions when the
widget is instantiated on a particular display.

The "configure_event" signal to take any necessary actions
when the widget changes size.

The "expose_event" signal to handle redrawing the contents of
the widget when a drawing area first comes on screen, or when it's covered by
another window and then uncovered (exposed). You can also force an expose
event by adding to the "damage region" of the drawing area's window using
the gtk.Widget.queue_draw_area()
method.